White Spot Syndrome Virus (WSSV) is an infectious pathogen of shrimp and other crustaceans. Currently, there are no effective vaccines and adequate treatments available against WSSV. More importantly, conventional immune route such as injection is not suitable for shrimp vaccination. Therefore, oral administration is good way to deliver WSSV vaccine.
The concept of edible vaccines was proposed by Prof. Dominic Lam and executed by him and his colleagues in early 1990s who first reported the expression of hepatitis B virus surface antigen (HBsAg) in tomato. Edible vaccines will be more acceptable because of its oral rather than injectable route of application. In contrast, producing the vaccines in plants could reduce the cost to less than a penny per dose, and simple fast food processing like drying and grinding could create non-perishable preparations without refrigeration. Further, Prof. Dominic Lam and his research team also focus on Lactococcus based vaccines which are used to prevent avian influenza infection.
Yeast surface display technology has been extensively developed for application in preventing virus affection. Recently, Saccharomyces cerevisiae (S. cerevisiae) surface display was used to develop H5N1 vaccine. P. pastoris cell surface display system was used to express VP28 and Rab7, respectively. Unfortunately, there no further animal test for this system. Importantly, there are no attempts to develop WSSV vaccine using S. cerevisiae display system which is more efficient than P. pastoris for viral antigen display.
Invertebrates lack true adaptive immunity and it solely depends on the primitive immunity called innate immunity. However, various innate immune molecules and mechanisms are identified in shrimp that plays potential role against invading bacterial, fungal and viral pathogens. Perceiving the shrimp innate immune mechanisms will contribute in developing effective vaccine strategies against major shrimp pathogens.
Collectively, we propose this invention that S. cerevisiae surface display system can be used to develop WSSV vaccine. To address this invention, VP28 and VP24 antigen genes are investigated by S. cerevisiae N-terminal surface display platforms.
Although the mechanism underlying the interaction between WSSV and host cells remain unknown, VP28 (27.5 kDa) and VP24 (22 kDa) are generally considered major capsid antigen proteins of WSSV, which are involved in the infection process as an attachment protein. This is the primary reason why VP28 and VP24 of the white spot syndrome virus (WSSV) have been used as candidate antigens for potential vaccines development.
Vaccination is currently the only method that can effectively stop the spread of WSSV in shrimps. Conventional platform for WSSV vaccine shows poor immunity. In the present invention, we describe a new type of potent WSSV vaccine based on yeast surface display system.
The present invention can provide an effective way to protect shrimps from WSSV infection and may also be used to produce edible vaccines for preventing and treating other infectious diseases in animals and humans.